Photolithography, which may be termed optical lithography or ultra-violet (UV) lithography in some contexts, is a process used to pattern extremely small features on an integrated circuit (IC). It uses light to transfer a geometric pattern from a photomask to a light-sensitive chemical “photoresist”, or simply “resist,” on the IC being manufactured. A series of chemical treatments then either engraves the geometric pattern into the material under the photoresist, or enables deposition of a new material in the desired pattern upon the material underneath the photo resist. In complex ICs, a wafer will go through photolithography a large number of times to buildup successive patterned layers that make up the resultant IC.